I step up my pace, determined to stay determined.

Only to run right into the back of a crocodile.

‘Keep moving, Year One. That means you too, Kyle Bannister.’

This crocodile consists of at least twenty children and five adults, carrying a neon rainbow of backpacks and swimming bags. They must have been to the university pool – the air around them smells of chlorine and fruit juice.

There’s no way I can squeeze past and no point turning back, as I’m more than halfway along the cut-through now.

Anyway I don’t want to go back because these children are adorable. Even Kyle Bannister, who turns round to pull a grotesque face at me, fingers stretching his mouth wide, nose wrinkled up so his join-the-dot freckles merge.

When I pull a face back at him, Kyle laughs so hard that I join in.

Their noises envelop me: giggles, shrieks, sandals slapping against paving stones. The kids are gloriously dishevelled, socks wonky, damp patches leaking through their school shirts.

And now I’m imagining the child Andrew and I might make together. A chatterbox daughter, like the girl whose voice rises above all the others, sharing every thought that pops into her head, asking why dolphins are shiny, why soft-play is stinky and why beans on toast are the most boring food in the galaxy. Or a son like the tallest boy at the head of the line: Andrew would have taught him chess and Scrabble and tag rugby.

Any child would be a gift. But the journey from the lab freezers holding our last two embryos to these earthbound individuals seems as hazardous as a trip to Mars.

I hear a tut, a long sigh, another tut. Somebody behind me.

I turn, expecting a grumpy old man, but instead—

YOU.

I’m sure I’ve never seen this man before – I’ve a good memory for people, and I’d certainly remember him – but the recognition is instant.

The sounds and smells of the kids fade until all I’m aware of is me and this man, whose face is criss-crossed with stress. Despite the frown, it’s a breathtaking face.

He hasn’t noticed me at all.

I try to look away, utterly discombobulated. He is extraordinary: movie-star beautiful, with the features of a troubled hero.

Right now, though, he’s not being very heroic. He’s scowling as he tries to dodge past Kyle and co, before realizing it’s a lost cause.

‘I bet you didn’t expect this kind of traffic jam,’ I say. It’s meant to be a joke, but it sounds deeply unfunny as soon as it’s out of my mouth.

‘I’m so bloody late. It’s a nightmare.’

His strained voice doesn’t match his laid-back clothes: fancy trainers, loose jeans, an artfully washed-out Primal Scream T-shirt. Already I’m doing my Gemma thing of making up stories for him: he’s a bank robber on his way to a heist. No, a tech billionaire running late for a make-or-break meeting to sell his business to the Chinese. Or a dad-to-be missing his wife’s labour?